The aim of this project is the understanding of neuronal processes by which a nervous system can extract complex information from a number of relatively simple inputs. Arthropod visual systems are ideally suited for such studies. The photoreceptor elements in such eyes are grouped into sub-units, or ommatidia, and the entire eye is made up of many such units. The ommatidia are amenable to study by a number of techniques and results of work over the past 15 years has led to an extensive knowledge of their physiology. This allows the investigation of cellular activity in regions of the nervous system serving the visual process under conditions where the input can be well controlled. Visual functions which require input from more than one receptor element, i.e., the wavelength sensitivity or movement detection, are selected for the study of integrative processes at the level of higher order neurons. The experimental approach is primarily electrophysiological using intra- and extracellular recording and marking techniques, however anatomical, developmental, and behavioral studies are also planned. The experimental animal in most experiments is the american cockroach Periplaneta. This animal has been selected because it possesses two spectrally distinct types of receptor element permitting the selective adaptation of one type while sparing the second. Other experimental animals include crustaceans and utilize the unusual arrangement of polarization sensitivities of receptor cells within a single ommatidium. These approaches have proved successful thus far and it is felt that this success is leading us toward the goal outlined above.